The library performs binary encoding/decoding, on-the-wire framing,
and error checking of control and data API frames. In other words
the library expects to communicate with an XBee modem that has AP
parameter = 2, indicating API frames with HDLC-like escape characters.
This mode provides for 8-bit transparent operation and is described in
Section 6 of ftp://ftp1.digi.com/support/documentation/90000866_C.pdf.

The library code is 100% pure; nothing here depends on the
IO monad and no particular modem device is assumed. The code
depends on the cereal package for serialization but is otherwise
pretty standard. The test suite is based on QuickCheck properties.